When my USB cable is connected, there is a lot of background noise from the master out, which changes from static to resonating to static as I move the master volume knob up (the level does not change much, the shape does) If I unplug the USB cable from the back of the unit, the noise drops to neglectable level.
I tried different cable and port, with no success. the noise is there even if the unit is turned off. It doesn't matter if I go through a sound card or direct to amp, I still get noise.
Does anyone else have the same issue or is my unit faulty?